For a variety of reasons the populations of many species of wild gastropod shellfish have diminished considerably over the last few decades. This applies especially to Haliotis rufescens, a species of abalone which historically thrived in the ocean off the coast of California. The demand for abalone as an edible delicacy primarily in the Far East continues to increase beyond the natural supply. This high demand and low supply situation has made the commercial farming of domesticated abalone economically attractive. Recently, abalone farming as well as aquaculture of a growing number of gastropod and non-gastropod marine animal species has developed into an industry of ever increasing commercial importance.
A stage of the abalone life cycle which significantly impacts the commercial viability of farming is the growth of the juveniles from a size of about 0.64-1.3 cm (0.25-0.5 in.) to maturity, i.e., about 7.6-10.2 cm (3-4 in.). Certain aspects of the care of abalone have made the maturation process difficult to implement in a commercial setting. For example, abalone's desire and ability to consume food changes with size during maturation. Consequently, the stock usually should be sorted as to size frequently to assure that all animals have optimum access to food. Also, the animals should live in a habitat favorable for growth similar to their natural environment. Some typically desirable habitat characteristics include adequately oxygenated, clean, pathogen-free, sea water, an ample supply of the preferred food, which is kelp, and a rock-like environmental surface on which the gastropods can cling as they forage.
Certain equipment has been developed to facilitate the growth of juvenile abalone. U.S. Pat. No. 4,320,717 of Rowley discloses an apparatus for growing sea life which uses multiple habitat modules vertically stacked on a support which rests on the sea floor. The apparatus further includes a system of feed risers such that each feed riser is adapted to feed a single module in the stack. Thus the disclosure appears to relate to an undersea captive habitat for growing abalone in segregated modules wherein the type of feed piped to each module can be controlled easily. The patented apparatus allows a module to be lowered onto the stack in any random order with assurance that the appropriate feed source will be connected to the module. However, the disclosed apparatus suffers from a significant drawback in that the modules are stacked. To retrieve a module positioned low in the stack for purposes of cleaning, repairing or harvesting the module or for any other reason, all higher modules must be removed first. This would seem to add to the labor and cost of servicing the apparatus disclosed in U.S. Pat. No. 4,320,717.
U.S. Pat. No. 5,377,624 of Craig et al. discloses a land-based abalone farming system. The patent refers to prior art grow-out tanks that typically were large rectangular seawater catch basins located outdoors. These grow-out tanks occupied much land. The '624 patent purportedly describes grow-out tanks with much better space utilization. The patented abalone farming system comprises a grow-out area that includes a set of vertically stacked, horizontally elongated tanks. The stack of tanks is connected to a seawater source and an outlet is provided for discharging spent seawater. A recirculation system permits discharged seawater to be selectively reclaimed at the outlet and fed back to the water supply. Land-based aquaculture facilities offer a high degree of convenience with respect to servicing the growing animals. Unfortunately, this convenience is frequently more than off set by the complicated and expensive equipment which must be operated to maintain a simulated natural environment for sea animals on a land-based site.
It is very desirable to have a robust, durable aquaculture apparatus which can be deployed at sea and which provides convenience for the care and protection of the cultured animals. It is also desirable to have an inexpensive aquaculture apparatus made from simple, low cost materials. An apparatus that is especially well suited to the aquaculture of juvenile abalone to harvesting at maturity has been discovered. Among other beneficial features, the novel apparatus especially provides durability; the ability to be made from commonly available inexpensive materials; flexibility to expand and contract production scale through modular construction; the ability to be deployed at sea in the animals' native environment; stability in turbulent ocean conditions; minimal visual impact on the seascape; easy accessibility to the growing animals at all stages of development for feeding, cleaning, sorting and harvesting; and the capability to easily modify the scale of operation.
Accordingly, there is now provided a floating aquaculture apparatus for deployment in a body of water comprising
(a) a plurality of substantially parallel columns; PA1 (b) a plurality of elongated modules between adjacent columns spaced apart longitudinally along the columns and oriented substantially perpendicular thereto, each module including: PA1 (c) means for anchoring the apparatus to the waterfloor.
(1) a buoyant elongated row member having a member length and being releasably attached at each of two ends to the adjacent columns; and PA2 (2) at least one negatively-buoyant rearing unit adapted to contain marine animals, the rearing unit being suspended from the row member above the waterfloor, wherein the buoyancy of the elongated row member is effective to neutralize the negative-buoyancy of all rearing units suspended therefrom; and
There is also provided a method of growing in captivity marine animals, and especially abalone which employs the floating aquaculture apparatus recited above.